#include <Columns/ColumnDecimal.h>
#include <Columns/ColumnsNumber.h>
#include <DataTypes/DataTypesDecimal.h>
#include <DataTypes/DataTypesNumber.h>
#include <Functions/FunctionFactory.h>

#include <Functions/array/FunctionArrayMapped.h>

namespace DB
{

namespace ErrorCodes
{
    extern const int ILLEGAL_TYPE_OF_ARGUMENT;
    extern const int ILLEGAL_COLUMN;
}

/** arrayCumSumNonNegative() - returns an array with cumulative sums of the original. (If value < 0 -> 0).
  */
struct ArrayCumSumNonNegativeImpl
{
    static bool needBoolean() { return false; }
    static bool needExpression() { return false; }
    static bool needOneArray() { return false; }

    static DataTypePtr getReturnType(const DataTypePtr & expression_return, const DataTypePtr & /*array_element*/)
    {
        WhichDataType which(expression_return);

        if (which.isUInt())
        {
            if (which.isNativeUInt())
                return std::make_shared<DataTypeArray>(std::make_shared<DataTypeUInt64>());
            if (which.isUInt128())
                return std::make_shared<DataTypeArray>(std::make_shared<DataTypeUInt128>());
            if (which.isUInt256())
                return std::make_shared<DataTypeArray>(std::make_shared<DataTypeUInt256>());
            UNREACHABLE();
        }

        if (which.isInt())
        {
            if (which.isNativeInt())
                return std::make_shared<DataTypeArray>(std::make_shared<DataTypeInt64>());
            if (which.isInt128())
                return std::make_shared<DataTypeArray>(std::make_shared<DataTypeInt128>());
            if (which.isInt256())
                return std::make_shared<DataTypeArray>(std::make_shared<DataTypeInt256>());
            UNREACHABLE();
        }

        if (which.isFloat())
            return std::make_shared<DataTypeArray>(std::make_shared<DataTypeFloat64>());

        if (which.isDecimal())
        {
            UInt32 scale = getDecimalScale(*expression_return);
            DataTypePtr nested;
            if (which.isDecimal256())
                nested = std::make_shared<DataTypeDecimal<Decimal256>>(DecimalUtils::max_precision<Decimal256>, scale);
            else
                nested = std::make_shared<DataTypeDecimal<Decimal128>>(DecimalUtils::max_precision<Decimal128>, scale);
            return std::make_shared<DataTypeArray>(nested);
        }

        throw Exception(ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT, "arrayCumSumNonNegativeImpl cannot add values of type {}", expression_return->getName());
    }


    template <typename Src, typename Dst>
    static void NO_SANITIZE_UNDEFINED implVector(
        size_t size, const IColumn::Offset * __restrict offsets, Dst * __restrict res_values, const Src * __restrict src_values)
    {
        size_t pos = 0;
        for (const auto * end = offsets + size; offsets < end; ++offsets)
        {
            auto offset = *offsets;
            Dst accumulated{};
            for (; pos < offset; ++pos)
            {
                accumulated += src_values[pos];
                if (accumulated < Dst{})
                    accumulated = {};
                res_values[pos] = accumulated;
            }
        }
    }


    template <typename Element, typename Result>
    static bool executeType(const ColumnPtr & mapped, const ColumnArray & array, ColumnPtr & res_ptr)
    {
        using ColVecType = ColumnVectorOrDecimal<Element>;
        using ColVecResult = ColumnVectorOrDecimal<Result>;

        const ColVecType * column = checkAndGetColumn<ColVecType>(&*mapped);

        if (!column)
            return false;

        const IColumn::Offsets & offsets = array.getOffsets();
        const typename ColVecType::Container & data = column->getData();

        typename ColVecResult::MutablePtr res_nested;
        if constexpr (is_decimal<Element>)
            res_nested = ColVecResult::create(0, column->getScale());
        else
            res_nested = ColVecResult::create();

        typename ColVecResult::Container & res_values = res_nested->getData();
        res_values.resize(data.size());
        implVector(offsets.size(), offsets.data(), res_values.data(), data.data());
        res_ptr = ColumnArray::create(std::move(res_nested), array.getOffsetsPtr());
        return true;
    }

    static ColumnPtr execute(const ColumnArray & array, ColumnPtr mapped)
    {
        ColumnPtr res;

        mapped = mapped->convertToFullColumnIfConst();
        if (executeType<UInt8, UInt64>(mapped, array, res) || executeType<UInt16, UInt64>(mapped, array, res)
            || executeType<UInt32, UInt64>(mapped, array, res) || executeType<UInt64, UInt64>(mapped, array, res)
            || executeType<UInt128, UInt128>(mapped, array, res) || executeType<UInt256, UInt256>(mapped, array, res)
            || executeType<Int8, Int64>(mapped, array, res) || executeType<Int16, Int64>(mapped, array, res)
            || executeType<Int32, Int64>(mapped, array, res) || executeType<Int64, Int64>(mapped, array, res)
            || executeType<Int128, Int128>(mapped, array, res) || executeType<Int256, Int256>(mapped, array, res)
            || executeType<Float32, Float64>(mapped, array, res) || executeType<Float64, Float64>(mapped, array, res)
            || executeType<Decimal32, Decimal128>(mapped, array, res) || executeType<Decimal64, Decimal128>(mapped, array, res)
            || executeType<Decimal128, Decimal128>(mapped, array, res) || executeType<Decimal256, Decimal256>(mapped, array, res))
            return res;
        throw Exception(ErrorCodes::ILLEGAL_COLUMN, "Unexpected column for arrayCumSumNonNegativeImpl: {}", mapped->getName());
    }
};

struct NameArrayCumSumNonNegative
{
    static constexpr auto name = "arrayCumSumNonNegative";
};
using FunctionArrayCumSumNonNegative = FunctionArrayMapped<ArrayCumSumNonNegativeImpl, NameArrayCumSumNonNegative>;

REGISTER_FUNCTION(ArrayCumSumNonNegative)
{
    FunctionDocumentation::Description description = "Returns an array of the partial (running) sums of the elements in the source array, replacing any negative running sum with zero. If a lambda function is specified, the sum is computed from applying the lambda to the array elements at each position.";
    FunctionDocumentation::Syntax syntax = "arrayCumSumNonNegative([func,] arr1[, arr2, ... , arrN])";
    FunctionDocumentation::Arguments arguments = {
        {"func", "Optional. A lambda function to apply to the array elements at each position.", {"Lambda function"}},
        {"arr1", "The source array of numeric values.", {"Array(T)"}},
        {"[arr2, ..., arrN]", "Optional. Additional arrays of the same size, passed as arguments to the lambda function if specified.", {"Array(T)"}}
    };
    FunctionDocumentation::ReturnedValue returned_value = {"Returns an array of the partial sums of the elements in the source array, with any negative running sum replaced by zero. The result type matches the input array's numeric type.", {"Array(T)"}};
    FunctionDocumentation::Examples examples = {
        {"Basic usage", "SELECT arrayCumSumNonNegative([1, 1, -4, 1]) AS res", "[1, 2, 0, 1]"},
        {"With lambda", "SELECT arrayCumSumNonNegative(x -> x * 2, [1, -2, 3]) AS res", "[2, 0, 6]"}
    };
    FunctionDocumentation::IntroducedIn introduced_in = {18, 12};
    FunctionDocumentation::Category category = FunctionDocumentation::Category::Array;
    FunctionDocumentation documentation = {description, syntax, arguments, returned_value, examples, introduced_in, category};

    factory.registerFunction<FunctionArrayCumSumNonNegative>(documentation);
}

}
